Computer Organization

Regardless of differences in physical appearance, virtually every computer may be envisioned as divided into six logical units or sections:


  1. Input unit. This is the "receiving" section of the computer. It obtains information (data and computer programs) from input devices and places this information at the disposal of the other units for processing. Most information is entered into computers through keyboards and mouse devices. Information also can be entered in many other ways, including by speaking to your computer, scanning images and having your computer receive information from a network, such as the Internet.
  2. Output unit. This is the "shipping" section of the computer. It takes information that the computer has processed and places it on various output devices to make the information available for use outside the computer. Most information output from computers today is displayed on screens, printed on paper or used to control other devices. Computers also can output their information to networks, such as the Internet.
  3. Memory unit. This is the rapid-access, relatively low-capacity "warehouse" section of the computer. It stores computer programs while they are being executed. It retains information that has been entered through the input unit, so that it will be immediately available for processing when needed. The memory unit also retains processed information until it can be placed on output devices by the output unit. Information in the memory unit is typically lost when the computer's power is turned off. The memory unit is often called either memory or primary memory. [Historically, this unit has been called "core memory," but that term is fading from use today.]
  4. Arithmetic and logic unit (ALU). This is the "manufacturing" section of the computer. It is responsible for performing calculations, such as addition, subtraction, multiplication and division. It contains the decision mechanisms that allow the computer, for example, to compare two items from the memory unit to determine whether they are equal.
  5. Central processing unit (CPU). This is the "administrative" section of the computer. It coordinates and supervises the operation of the other sections. The CPU tells the input unit when information should be read into the memory unit, tells the ALU when information from the memory unit should be used in calculations and tells the output unit when to send information from the memory unit to certain output devices. Many of today's computers have multiple CPUs and, hence, can perform many operations simultaneouslysuch computers are called multiprocessors.
  6. Secondary storage unit. This is the long-term, high-capacity "warehousing" section of the computer. Programs or data not actively being used by the other units normally are placed on secondary storage devices, such as your hard drive, until they are again needed, possibly hours, days, months or even years later. Information in secondary storage takes much longer to access than information in primary memory, but the cost per unit of secondary storage is much less than that of primary memory. Other secondary storage devices include CDs and DVDs, which can hold hundreds of millions of characters and billions of characters, respectively.

Introduction to Computers, the Internet and World Wide Web

Introduction to C++ Programming

Introduction to Classes and Objects

Control Statements: Part 1

Control Statements: Part 2

Functions and an Introduction to Recursion

Arrays and Vectors

Pointers and Pointer-Based Strings

Classes: A Deeper Look, Part 1

Classes: A Deeper Look, Part 2

Operator Overloading; String and Array Objects

Object-Oriented Programming: Inheritance

Object-Oriented Programming: Polymorphism

Templates

Stream Input/Output

Exception Handling

File Processing

Class string and String Stream Processing

Web Programming

Searching and Sorting

Data Structures

Bits, Characters, C-Strings and structs

Standard Template Library (STL)

Other Topics

Appendix A. Operator Precedence and Associativity Chart

Appendix B. ASCII Character Set

Appendix C. Fundamental Types

Appendix D. Number Systems

Appendix E. C Legacy Code Topics

Appendix F. Preprocessor

Appendix G. ATM Case Study Code

Appendix H. UML 2: Additional Diagram Types

Appendix I. C++ Internet and Web Resources

Appendix J. Introduction to XHTML

Appendix K. XHTML Special Characters

Appendix L. Using the Visual Studio .NET Debugger

Appendix M. Using the GNU C++ Debugger

Bibliography



C++ How to Program
C++ How to Program (5th Edition)
ISBN: 0131857576
EAN: 2147483647
Year: 2004
Pages: 627

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